290 
PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 
reach the point of pupation, and from them a very few Zygobothria 
adults (fig. 69) were reared. There was no ground for doubting that the 
tachinids actually issued from the imported caterpillars of the brown- 
tail moth and that they had actually been present as hibernating 
larvae within the caterpillars when they were received from Europe, 
but at the same time the circumstance seemed so improbable as to be 
refused immediate credence. Confirmation of the records was accord- 
ingly sought in 1908, and preparations were made to carry large 
numbers of the caterpillars from imported nests through to maturity 
in the large trays, already mentioned in the discussion of Apanteles. 
For a time everything went well, and the caterpillars passed through 
three of the spring stages and assumed the colors characteristic of the 
last with scarcely any mortality. 
Then, for some reason, they ceased 
to feed freely, and began to die, 
and even those which did feed 
ceased to grow. Eventually prac- 
tically all of them died, but of the 
few which survived to pupate, a 
very few contained the parasite, 
and although only about half a 
dozen of the adult Zygobothria 
were reared, they were sufficient 
to prove beyond question the va- 
lidity of the earlier conclusions. 
The death of the caterpillars from 
imported nests in 1906 was sup- 
posed to be due to the epidemic 
of fungous disease which affected 
those in confinement quite as gen- 
erally as those in the open, and in 
1907 death was presumed to be 
the result of the unsanitary con- 
ditions which resulted from the use of the closed cages. In casting 
about for a cause in 1908, the drying of the food in the open trays 
before the caterpillars fed upon it was deemed to be sufficient, and 
consequently, in 1909, it was determined to use extraordinary precau- 
( ions and to rear a large number of the tachinids if it were possible. 
In the early spring of 1909 a considerable number of the imported 
caterpillars was dissected before they began to feed, and in some lots 
a high percentage was found to contain the hibernating larvse of the 
Zygobothria (fig. 63, p. 264). These lots were to be given especial 
care, and little doubt w as felt as to the success of the outcome, because 
Fig. 6X — Zygobothria nidicola: Adult female, with 
front view of head above and side view below. 
Much enlarged. (Original.) 
